1. Field of the Invention
The invention relates to the field of treadmills, and in particular to the bodies or chassis by which the treadmill belt is supported.
2. Description of the Prior Art
A treadmill is an exercise device which permits walking or running by moving a continuous belt along the length of a chassis. The belt which is controlled by a motor and appropriate control electronics slides over a supporting deck. The belt is flexible and is unable to rigidly support the weight of the user. As the exerciser or user walks or runs on the belt, the belt is pressed against the underlying supporting deck to provide mechanical support for the exerciser since the belt while substantially nonextensible, is typically made of a reinforced flexible synthetic rubber.
Such supporting decks, in turn, are rigidly affixed to or supported by the treadmill chassis, thereby effectively providing a hard moving surface for the exerciser to walk or run on. To minimize friction and wear, the surface of the supporting deck in contact with the moving belt is provided with a waxed and/or polished surface. In time, this surface becomes worn or depleted and the amount of friction between the moving belt and deck increases. Therefore, the supporting deck must either be resurfaced or replaced periodically depending on wear. In the case of treadmills used in commercial exercising salons, the typical life time of the supporting deck is approximately six months.
In addition, because it provides rigid support, the shock of the user's step is reflected by the supporting deck back to the user's foot, ankle and leg in the same manner as reactive forces are imposed on a walker, jogger or runner exercising on hard paved streets or sidewalks. Over a long period of time, this shock can have deleterious effects to the joints of some exercisers.
What is needed is some type of support for a moving treadmill surface that provides rigid support for the belt and exerciser. Further, what is needed is a supporting surface for a treadmill belt which is not characterized by the hard shocks which are normally encountered when walking upon a rigidly supported treadmill belt.
The treadmill belt is intended to be tensioned by a predetermined amount of stretch depending upon the inherent material characteristics of the belt. The belt is typical supplied by the manufacturer with a predetermined percentage of stretch required. If tensioned too highly, it may bind on the treadmill. If tensioned too loosely, it may slip and wear excessively. Tensioning is conventionally accomplished by adjusting the distance between the belt rollers (not shown) at each end of the treadmill. Prior art methods for tensioning include the use of specialized tension meters to measure the tensile force across the width of the belt. Such meters are difficult to use properly, expensive, and generally not available to personnel who maintain the treadmills or change the belts. Otherwise, tension is adjusted by trial and error to a tension which seems to work is achieved.
Therefore, what is needed is some type of means and method which can accurately adjust belt tension, even when a new belt with new characteristics is installed.